Connecting two subwoofers

A quick look at the DB1 manual pdf shows RCA unbalanced inputs for both mono & stereo. 

When I used to run a lone sub on the 2ch end of my system, before I migrated to the option of a speaker level connection, I used a Naim supplied and built 4pin DIN to 2RCA sub lead.  This went from the pre's PSU to the sub. It was a 'slugged' lead with resistors in it to prevent destabilising the impedances between the pre and power amps. 

Looking at you profile it seems that you're not using a Naim power amp, so I'm not sure if you're using just one or two of the three available PSU sockets to feed your power amps. 

So, you'll either need a single 4DIN-2RCA sub lead, built to split so it'll reach both subs.... OR, a pair of mono ones if you feed your power amp from a single socket and are happy to use up the other two. 

From here on in it's initially a case of set up by the Bowers book as per their suggestions to match the sub to the 802s, followed by lots of listening and tweaking of the EQ and Low pass filter. 

Enjoy, and hope this helps. 

Mike

Thanks for the answer.  I am just using one of the sockets for my Plinius power amp.  Is there a perceived benefit between using one stereo cable vs. two monos?  I just have the one DB1 for now and adding the second one next week.  It is interesting you mentioned the issue of the destabilizing impedances because I have the stereo cable but don't believe I have a cable with the slugged lead, and if the DB1 goes to sleep mode it causes a buzzing in my power amp.  It was the reason why I was uncertain in how I go from one to two and if I was using the correct cable.  Another silly question is if connecting with two mono cables how do you ensure you are outputting left to the left sub and right to the right sub? Or does it not matter?

Thanks, again.

Ok.. first question last... A pair of mono subleads do need to be made as a left and right set, pretty much as naim make specific left and right leads for a NAP300 or NAP500.

In practice a single stereo cable to a lone sub would sound better. Not sure that two leads to two cables will be much worse though than having a stereo lead made with an appropriate 'split point' to easily reach both subs. 

As for stabilising the impedances, who made the lead that connects to your Plinius? If it's not a Naim lead, perhaps worth getting a full set to power amp and both subs made, and they can be tailored to work together? I'm sure naim would do this in order to protect their end of the system. 

All the best

Mike

Thanks, Mike.  Very helpful.

Naimheadhunter,

In my experience there are important gains to be made using two subwoofers in stereo.  On some recordings it may matter little, but where the bass is not deliberately mixed to mono there can be spatial cues that (perhaps somewhat artificially) hint at the acoustical space.  So best to wire them with left to one channel and right to another.  There are likely gains from exciting the room modes from two locations - but this is of course room and position dependent.

Of course, consider experimenting and go with what sounds best.  Be sure to listen to a wide variety of recordings and refrain from quick judgements based on only a single recording.

Cheers,

Charlie

It's worth bearing in mind that you need to be a bit careful when running a long i/c cable from the pre-out on a Naim PSU - it's only designed to run short lengths.  The cable usually needs to be slugged (as per the official Naim sub lead) and even then I'm fairly sure I can detect a performance hit against not having the sub cable connected. Running two such cables doubles the problem.

Thanks, Charlie.

So what do you recommend, Richard?

If you must have subwoofers then I'd recommend those that have a high level input.

Otherwise, I would have your dealer confer with Naim as to the most appropriate sub leads specs.

One could use a resistor attenuator at the sub line-level input, allowing to be driven from the speaker terminals.  I can't say offhand what the resistor values should be, but perhaps a 1:10 attenuation or so is appropriate?  This suggestion calls for some skill level, so if that is daunting get help from your dealer as Richard wisely suggests.